lber-encode(3) — Linux manual page


LBER_ENCODE(3)            Library Functions Manual            LBER_ENCODE(3)

NAME         top

       ber_alloc_t,    ber_flush,   ber_flush2,   ber_printf,   ber_put_int,
       ber_put_enum,    ber_put_ostring,    ber_put_string,    ber_put_null,
       ber_put_boolean,   ber_put_bitstring,  ber_start_seq,  ber_start_set,
       ber_put_seq, ber_put_set - OpenLDAP LBER  simplified  Basic  Encoding
       Rules library routines for encoding

LIBRARY         top

       OpenLDAP LBER (liblber, -llber)

SYNOPSIS         top

       #include <lber.h>

       BerElement *ber_alloc_t(int options);

       int ber_flush(Sockbuf *sb, BerElement *ber, int freeit);

       int ber_flush2(Sockbuf *sb, BerElement *ber, int freeit);

       int ber_printf(BerElement *ber, const char *fmt, ...);

       int ber_put_int(BerElement *ber, ber_int_t num, ber_tag_t tag);

       int ber_put_enum(BerElement *ber, ber_int_t num, ber_tag_t tag);

       int ber_put_ostring(BerElement *ber, const char *str, ber_len_t len,
       ber_tag_t tag);

       int ber_put_string(BerElement *ber, const char *str, ber_tag_t tag);

       int ber_put_null(BerElement *ber, ber_tag_t tag);

       int ber_put_boolean(BerElement *ber, ber_int_t bool, ber_tag_t tag);

       int ber_put_bitstring(BerElement *ber, const char *str, ber_len_t
       blen, ber_tag_t tag);

       int ber_start_seq(BerElement *ber, ber_tag_t tag);

       int ber_start_set(BerElement *ber, ber_tag_t tag);

       int ber_put_seq(BerElement *ber);

       int ber_put_set(BerElement *ber);

DESCRIPTION         top

       These routines provide a subroutine interface to a simplified
       implementation of the Basic Encoding Rules of ASN.1.  The version of
       BER these routines support is the one defined for the LDAP protocol.
       The encoding rules are the same as BER, except that only definite
       form lengths are used, and bitstrings and octet strings are always
       encoded in primitive form.  This man page describes the encoding
       routines in the lber library.  See lber-decode(3) for details on the
       corresponding decoding routines.  Consult lber-types(3) for
       information about types, allocators, and deallocators.

       Normally, the only routines that need to be called by an application
       are ber_alloc_t() to allocate a BER element for encoding,
       ber_printf() to do the actual encoding, and ber_flush2() to actually
       write the element.  The other routines are provided for those
       applications that need more control than ber_printf() provides.  In
       general, these routines return the length of the element encoded, or
       -1 if an error occurred.

       The ber_alloc_t() routine is used to allocate a new BER element.  It
       should be called with an argument of LBER_USE_DER.

       The ber_flush2() routine is used to actually write the element to a
       socket (or file) descriptor, once it has been fully encoded (using
       ber_printf() and friends).  See lber-sockbuf(3) for more details on
       the Sockbuf implementation of the sb parameter.  If the freeit
       parameter is non-zero, the supplied ber will be freed.  If
       LBER_FLUSH_FREE_ON_SUCCESS is used, the ber is only freed when
       successfully flushed, otherwise it is left intact; if
       LBER_FLUSH_FREE_ON_ERROR is used, the ber is only freed when an error
       occurs, otherwise it is left intact; if LBER_FLUSH_FREE_ALWAYS is
       used, the ber is freed anyway.  This function differs from the
       original ber_flush(3) function, whose behavior corresponds to that
       indicated for LBER_FLUSH_FREE_ON_SUCCESS.  Note that in the future,
       the behavior of ber_flush(3) with freeit non-zero might change into
       that of ber_flush2(3) with freeit set to LBER_FLUSH_FREE_ALWAYS.

       The ber_printf() routine is used to encode a BER element in much the
       same way that sprintf(3) works.  One important difference, though, is
       that some state information is kept with the ber parameter so that
       multiple calls can be made to ber_printf() to append things to the
       end of the BER element.  Ber_printf() writes to ber, a pointer to a
       BerElement such as returned by ber_alloc_t().  It interprets and
       formats its arguments according to the format string fmt.  The format
       string can contain the following characters:

              b  Boolean.  An ber_int_t parameter should be supplied.  A
                 boolean element is output.

              e  Enumeration.  An ber_int_t parameter should be supplied.
                 An enumeration element is output.

              i  Integer.  An ber_int_t parameter should be supplied.  An
                 integer element is output.

              B  Bitstring.  A char * pointer to the start of the bitstring
                 is supplied, followed by the number of bits in the
                 bitstring.  A bitstring element is output.

              n  Null.  No parameter is required.  A null element is output.

              o  Octet string.  A char * is supplied, followed by the length
                 of the string pointed to.  An octet string element is

              O  Octet string.  A struct berval * is supplied.  An octet
                 string element is output.

              s  Octet string.  A null-terminated string is supplied.  An
                 octet string element is output, not including the trailing
                 NULL octet.

              t  Tag.  A ber_tag_t specifying the tag to give the next
                 element is provided.  This works across calls.

              v  Several octet strings.  A null-terminated array of char *'s
                 is supplied.  Note that a construct like '{v}' is required
                 to get an actual SEQUENCE OF octet strings.

              V  Several octet strings.  A null-terminated array of struct
                 berval *'s is supplied.  Note that a construct like '{V}'
                 is required to get an actual SEQUENCE OF octet strings.

              W  Several octet strings.  An array of struct berval's is
                 supplied.  The array is terminated by a struct berval with
                 a NULL bv_val.  Note that a construct like '{W}' is
                 required to get an actual SEQUENCE OF octet strings.

              {  Begin sequence.  No parameter is required.

              }  End sequence.  No parameter is required.

              [  Begin set.  No parameter is required.

              ]  End set.  No parameter is required.

       The ber_put_int() routine writes the integer element num to the BER
       element ber.

       The ber_put_enum() routine writes the enumeration element num to the
       BER element ber.

       The ber_put_boolean() routine writes the boolean value given by bool
       to the BER element.

       The ber_put_bitstring() routine writes blen bits starting at str as a
       bitstring value to the given BER element.  Note that blen is the
       length in bits of the bitstring.

       The ber_put_ostring() routine writes len bytes starting at str to the
       BER element as an octet string.

       The ber_put_string() routine writes the null-terminated string (minus
       the terminating ' ') to the BER element as an octet string.

       The ber_put_null() routine writes a NULL element to the BER element.

       The ber_start_seq() routine is used to start a sequence in the BER
       element.  The ber_start_set() routine works similarly.  The end of
       the sequence or set is marked by the nearest matching call to
       ber_put_seq() or ber_put_set(), respectively.

EXAMPLES         top

       Assuming the following variable declarations, and that the variables
       have been assigned appropriately, an lber encoding of the following
       ASN.1 object:

             AlmostASearchRequest := SEQUENCE {
                 baseObject      DistinguishedName,
                 scope           ENUMERATED {
                     baseObject    (0),
                     singleLevel   (1),
                     wholeSubtree  (2)
                 derefAliases    ENUMERATED {
                     neverDerefaliases   (0),
                     derefInSearching    (1),
                     derefFindingBaseObj (2),
                     alwaysDerefAliases  (3)
                 sizelimit       INTEGER (0 .. 65535),
                 timelimit       INTEGER (0 .. 65535),
                 attrsOnly       BOOLEAN,
                 attributes      SEQUENCE OF AttributeType

       can be achieved like so:

             int rc;
             ber_int_t    scope, ali, size, time, attrsonly;
             char   *dn, **attrs;
             BerElement *ber;

             /* ... fill in values ... */

             ber = ber_alloc_t( LBER_USE_DER );

             if ( ber == NULL ) {
                     /* error */

             rc = ber_printf( ber, "{siiiib{v}}", dn, scope, ali,
                 size, time, attrsonly, attrs );

             if( rc == -1 ) {
                     /* error */
             } else {
                     /* success */

ERRORS         top

       If an error occurs during encoding, generally these routines return

NOTES         top

       The return values for all of these functions are declared in the
       <lber.h> header file.

SEE ALSO         top

       lber-decode(3), lber-memory(3), lber-sockbuf(3), lber-types(3)


       OpenLDAP Software is developed and maintained by The OpenLDAP Project
       <>.  OpenLDAP Software is derived from the
       University of Michigan LDAP 3.3 Release.

COLOPHON         top

       This page is part of the OpenLDAP (an open source implementation of
       the Lightweight Directory Access Protocol) project.  Information
       about the project can be found at ⟨⟩.  If you
       have a bug report for this manual page, see
       ⟨⟩.  This page was obtained from the
       project's upstream Git repository
       ⟨⟩ on 2020-11-01.  (At
       that time, the date of the most recent commit that was found in the
       repository was 2020-10-30.)  If you discover any rendering problems
       in this HTML version of the page, or you believe there is a better or
       more up-to-date source for the page, or you have corrections or im‐
       provements to the information in this COLOPHON (which is not part of
       the original manual page), send a mail to

OpenLDAP LDVERSION               RELEASEDATE                  LBER_ENCODE(3)

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